Image search engines provide an easy and efficient way of searching large collections of images. In operation, image search engines may receive text search queries as user input and retrieve images that match the text queries in response. The text queries may include one or more keywords that identify an object that is sought to be depicted in images retrieved by the search engines. Thus, for example, when a search engine is provided with a query “Eiffel Tower”, the image search engine may desirably retrieve images of the Eiffel Tower.